Niels Bohr, the bohr model was created in 1915, known as the planetary model. The neutrons and protons are in the middle of the diagram and "stuck" together. Electrons circle around the outside, kind of orbiting the protons and neutrons. Here are some pictures of what it looks like, for example hydrogen-1 helium-4, lithium-6, and sodium-22: http://nothingnerdy.wikispaces.com/file/view/bohr_atom.jpg/88197115/bohr_atom.jpg
He discovered the model by realizing some of the detrimental attributes of Rutherford's atom. He found out that Rutherford's atom did not include set energy levels of electrons. Prior discoveries had already proved that an electron loses energy as it spirals around the atom until it final collapes onto the atom. Taking this knowledge he created this model. "He argued that each electron had fixed amount of energy, which corresponded to its fixed orbit." When an electron absorbs energy, it moves to the next higher orbit. Bohr worked with orbits, but at the lowest orbit, there is something called a zero area elipses. Instead of the electron circling in a circle, it moves kind of back and forth not around it.
"The idea of an electron flying around in little circles turned out to have lots of problems, and physicists were eventually forced to discard that model. The concept of "special orbits" was extremely useful but the concept of the orbits was just not going to be used anymore. Instead, electrons would be in special energy levels because sometimes orbits have the same energy and this would not emit radiation." http://www.colorado.edu/physics/2000/quantumzone/bohr2.html
|| Ephoton = Einitial - Efinal
This formula can be used to determine the energy of the photon emitted (+) or absorbed(-).
Ephoton = hf where h = 6.6 x 10-34 Js or 4.14 x 10-15 eVs
This formula can be used to determine the energy of a photon if you know the frequency of it. Planck's constant, h, can be used in terms of Joule(s) or eV(s). (note: the Regents reference table only gives it in terms of Js)
(II) Describe the experiment(s) that led to the development of this model. How did evidence change the model of the atom compared to the previously accepted model?
http://nothingnerdy.wikispaces.com/file/view/bohr_atom.jpg/88197115/bohr_atom.jpg
He discovered the model by realizing some of the detrimental attributes of Rutherford's atom. He found out that Rutherford's atom did not include set energy levels of electrons. Prior discoveries had already proved that an electron loses energy as it spirals around the atom until it final collapes onto the atom. Taking this knowledge he created this model. "He argued that each electron had fixed amount of energy, which corresponded to its fixed orbit." When an electron absorbs energy, it moves to the next higher orbit. Bohr worked with orbits, but at the lowest orbit, there is something called a zero area elipses. Instead of the electron circling in a circle, it moves kind of back and forth not around it.
"The idea of an electron flying around in little circles turned out to have lots of problems, and physicists were eventually forced to discard that model. The concept of "special orbits" was extremely useful but the concept of the orbits was just not going to be used anymore. Instead, electrons would be in special energy levels because sometimes orbits have the same energy and this would not emit radiation."
http://www.colorado.edu/physics/2000/quantumzone/bohr2.html
|| Ephoton = Einitial - Efinal
where h = 6.6 x 10-34 Js
or 4.14 x 10-15 eVs
(note: the Regents reference table only gives it in terms of Js)
http://www.regentsprep.org/regents/physics/phys05/catomodel/bohr.htm
(II) Describe the experiment(s) that led to the development of this model. How did evidence change the model of the atom compared to the previously accepted model?
What led to Bohr to invent this system was to explain how light was produced and to explain why it emitted those specific spectra (color of light). http://www.colorado.edu/physics/2000/quantumzone/bohr2.html